38 Netfinity and Windows 2000 Integration Guide
When you install the optional Netfinity Fibre Channel Failsafe RAID Controller
(part 01K7296), the two controllers are set up as a redundant pair. If one fails, the
other takes over the failed controller’s functions and the unit as a whole continues
to operate. You can then replace the failed controller while the unit is still
functioning and resume normal operation.
The redundant controllers can be configured in two ways:
• In an active/passive configuration, one controller handles all the I/O from the
host and the other controller is held as a spare, taking over if the first controller
fails.
• In active/active configuration, both controllers handle I/O from the host and
each controller is assigned specific LUNs to service. If one controller fails, the
other takes over the failed controller’s assigned LUNs. This is the
recommended configuration, since using two controllers for I/O is usually
faster than using a single controller.
Note: When the controller is configured to active/active mode, the cache is
split in half and mirrored between the two sides. Consequently, only 64 MB of
cache is available for use instead of 128 MB.
The mode selection is made from within the SYMplicity Storage Manager
software.
As shown in Figure 22, the controller unit has two RS-232 diagnostic ports, one
for each controller that can be used with a terminal emulator such as
HyperTerminal to service the unit. It also has two Ethernet AUI ports, one for each
controller, which can be used to remotely access the array across the network for
configuring and monitoring the array using Network SYMplicity Storage Manager.
Tip: Versions of HyperTerminal earlier than V3.0 do not have the function to issue
a break. If you need to do this, turn the RAID controller unit off and back on again.
Alternatively use another terminal emulator. You can download a 90-day trial of
HyperTerminal from http://www.hilgraeve.com/.
2.3.6 Fibre Channel cables
The Netfinity Fibre Channel PCI Adapter and Netfinity Fibre Channel RAID
Controller both support short-wave cables, but the Netfinity Fibre Channel Hub
supports both short-wave and long-wave cables.
The short-wave connections can be up to 500 meters long, and the long-wave
cables can be up to 10 km long. Only hub-to-hub connections can use long-wave
cables.
There are two short-wave cables available from IBM, a 5 meter cable (part
03K9306) and a 25 meter cable (part 03K9305). These cables are 50 microns in
diameter. The 62.5 micron short-wave cables are not supported. See 2.3.6, “Fibre
Channel cables” on page 38 for more information on cables.
All Netfinity Fibre Channel devices use cables with SC connectors (SC stands for
standardized connector). These connectors are keyed and can only be plugged in
one way.
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